The lawmaker said it was possible the coalition would be led by President Rodrigo Duterte, Carpio, and Arroyo.

Andaya said it was now up to PDP-Laban to make adjustments in leadership to ensure they get to keep their members.

He added, PDP-Laban members want to join a new party as they are worried about who would nominate them once they file their candidacy for the coming elections.

That was supposed to be ousted House Speaker Pantaleon Alvarez's job, but members withdrew their support for him.

Andaya also said some members felt disenchanted after the party began expanding in the provinces, as they felt the party leadership in some areas were given to their rivals, with Alvarez unable to protect their interests.

For his part, PDP-Laban president Senator Koko Pimentel said the party remains intact and no reorganization was in the offing. But he admitted that talks of members leaving the party are a distraction to creating the PDP-Laban's senatorial line-up.

Rep. Albee Benitez of the Visayan bloc at the House told CNN Philippines' On The Record that there was no talk of migrating to a new party when he and other supporters of Arroyo gathered for lunch with the new Speaker on Tuesday.

He added that PDP-Laban is still the ruling party, with the President Duterte remaining as its chairman.

Arroyo unseated her predecessor Pantaleon Alvarez, PDP-Laban's Secretary General, after more than 200 lawmakers voted for a change in leadership on July 23.

Carpio was reported to have had a hand in the ouster, but she refused to comment.

Is President Rodrigo Duterte involved?

But Senator Franklin Drilon believes President Rodrigo Duterte must be aware of the change in allegiance in the House.

"If the reports were true, I don't think Mayor Sara Duterte would work on the change of the leadership without, at the very least, the knowledge of the President. That is the reality that we face. That is not only true today, that is also true for the past administrations and Congresses," he added.

The Senate minority leader also said what happened is "simply local politics translated and transformed into the national scene."

"The episode in the House of Representative necessitates and justifies the passage of a political party system act," Drilon said at the Kapihan sa Senado on Thursday.

Drilon authored Senate Bill 226 or the Political Party System Act, which aims to penalize political "turncoats" by prohibiting them from running under a political party for the next election after the switch.